The present invention relates to an electronic board system as an information input/output device used with a computer, and to a coordinates-inputting pen employing an infrared-ray detecting system used with the electronic board. More particularly, the present invention relates to processing of a signal indicating timing upon detecting a light beam with a pen and to processing of a switch signal generated upon clicking a button provided on the pen, in an electronic board which detects a location of a pen by scanning over the electronic board with a light beam.
An electronic board is an information input/output device used with computers, onto which a display output from the computer is projected from front or back of the board (screen) with a projector, while a pointed location or a trace of a coordinates-inputting pen on the board is incorporated as coordinate data.
With an electronic board employing a laser scanning system, a large display surface such as a screen is scanned with scanning beams generated by two laser scanners provided on upper left and right corners of the board. Examples of method for detecting a signal indicating timing upon capturing the scanning beams with the coordinates-inputting pen to specify the location of the coordinates-inputting pen include: (a) a method in which the scanning beams are reflected off a reflecting surface of a tip of the coordinates-inputting pen, and then the reflected beam is detected at a fixed point on the board; (b) a method in which an infrared signal from the coordinates-inputting pen is directed to a screen to detect the signal with a rear projector behind the screen; and (c) a method in which a scanning beam detection signal detected with the coordinates-inputting pen is sent out as an electric signal from the coordinates-inputting pen via a connecting wire.
However, the above-described methods for detecting the timing signals have the following defectives, respectively.
(a) According to the method of detecting a scanning beam reflected off the coordinates-inputting pen two infrared scanning beams have to spot on the coordinates-inputting pen to detect a pen-press. Thus, pen-press signals are received with low precision. A click button such as a mouse cannot be provided. When the coordinates-inputting pen is inclined, even by a slight angle, detection of the location of the pen becomes difficult. Since the height of the beam from the surface of the electronic board is critical for scanning over the electronic board, flatness of the surface of the electronic board and precise finishing of the optical scanning system need to strictly be managed, which results in high cost.
(b) The method of directing the infrared signal from the coordinates-inputting pen to the screen in front of the rear projector cannot be applied to a board using a front projector. In addition, a distance necessary for the light beam from the pen to approach the board differs depending on the optical structures including the screen (e.g., the screen size) and the internal rear projector. Accordingly, a design specification of the coordinates-inputting pen varies according to the specification of the rear projector, which results in high cost.
(c) According to the method of sending out the electronic signal from the coordinates-inputting pen via the connecting wire, the connecting wire often becomes an obstacle. Furthermore, in use for years, the connecting wire may wear and become useless due to disconnection or contact failure. When a front projector system is employed, the connecting wire may cast a shadow on the electronic board, which makes it hard for the user to see the screen.
The objective of the present invention is to provide an electronic board having none of the above-described conventional defectives, which is able to send, without a connecting wire, click signals generated upon manipulating multiple switches provided on the coordinates-inputting pen and a timing signal upon detecting the infrared scanning beam, to an electronic board controller provided at a fixed position on the board.
The present invention also has an objective of improving safety of the electronic board by limiting the infrared scanning beam for specifying the coordinates of the coordinates-inputting pen to be generated only at the time of drawing.
Another objective of the present invention is to provide an electronic board which incorporates data in a satisfactorily quick response to drawing with the coordinates-inputting pen and which accurately transfers a click switch output or a pen-press signal from the coordinates-inputting pen to an electronic board controller provided at a fixed position.
Yet another objective of the present invention is to provide an electronic board which is capable of accurately sending a click signal or a timing signal upon detecting an infrared scanning beam to an electronic board controller, even when the coordinates-inputting pen is inclined during the drawing.
According to the present invention, in order to accomplish the above-described objectives, light-emitting elements which can emit visible light or infrared light are provided on a coordinates-inputting pen. A timing signal upon detecting an infrared scanning beam with the coordinates-inputting pen and a click signal generated upon manipulating one of multiple switches provided on the pen are sent out on a modulated light from the light-emitting element so as to be received by a light receiver arranged at a fixed position. A plurality of light-emitting elements are provided on an external surface of the coordinates-inputting pen. The light-emitting elements used have broad spatial radiation pattern in the shaft direction of the pen so that the emitted light is sufficient to reach and activate the receivers at fixed points (e.g., provided along the periphery of the board) even if the pen is inclined during the drawing. Moreover, since the coordinates-inputting pen may rotate with respect to its axis upon use, the radiation pattern around the axis of the pen is determined considering the position and the number of the light receivers provided at fixed positions (e.g., provided along the periphery of the board).
However, simple use of light for signal transmission from the coordinates-inputting pen causes interference in the signal even if an influence by foreign light is limited by use of an optical filter or the like. Accordingly, signals to be transmitted are encoded to transmit modulated light. In addition, the wavelengths of the infrared scanning beams used for detecting the location of the pen and light used for signal transmission from the pen are made different. In order to prevent transmission error, in addition to the timing signal upon capturing the scanning light and the ON/OFF signal of the pen switch, recognition codes (ID bits) are also added to the signal to be transmitted from the pen.
As to the timing of capturing the scanning light, the light received by the coordinates-inputting pen needs to pass the light receiver provided at a fixed point and be modulated as a signal within an accuracy of micro-second order. According to the present invention, the timing signal upon capturing the scanning light with the coordinates-inputting pen, a click switch output of the pen and a pen-press signal are converted into simple codes so as to save time for modulating/demodulating. Moreover, in order to avoid the timing signal upon capturing the scanning light to be generated with time error, a code (bit) indicating timing of capturing the scanning light is added to the transmitted codes as a leading code. When this code (bit) is received, time count that has started from the reference point of the scanning is stopped (this count corresponds to a scanning angle), and the recognition codes (ID bits) attached to the transmitted codes are read. When the transmitted codes are judged valid, the time count value is subjected to the subsequent processing to specify the location coordinates of the coordinates-inputting pen. There may be, however, a slight time lag between the timing of capturing the scanning light and the stopping of the above-described time count (the count corresponding to the scanning angle). Therefore, the circuits have to be arranged to always give a constant time lag, and the time count has to be corrected. For example, when the time count is always 10 micro-seconds late, the time count value is always subtracted of 10 micro-seconds before specifying the scanning angle. Based on this scanning angle, the coordinates are calculated.
The light emission from the infrared scanning beam sources can be controlled by controlling the pen-press signal which is generated when the coordinates-inputting pen touches the board. By doing so, the infrared scanning beam sources emit light only when the coordinates-inputting pen is used with the electronic board for drawing (or writing), otherwise the sources do not emit light.
Specifically, an electronic board system of the present invention comprises: a board including first and second infrared scanning beam generators for alternately generating infrared scanning beams for rotational scanning; a coordinates-inputting pen including a photodetector for detecting the infrared scanning beams, a pen-press switch for detecting a pen-press against the board, an electronic circuit for outputting time sequential signals based on the detection signal from the photodetector and the ON/OFF signals of the pen-press switch, and a light-emitting element for generating an optical signal based on the time sequential signals output from the electronic circuit; a light receiver arranged at a position away from the coordinates-inputting pen, for detecting the optical signal generated from the light-emitting element of the coordinates-inputting pen; and an electronic board controller for calculating the coordinates of the coordinates-inputting pen based on the output of the light receiver.
Alternatively, an electronic board system of the invention comprises: a board including first and second infrared scanning beam generators for alternately generating infrared scanning beams for rotational scanning, a first reference sensor for generating a first reference signal upon detecting the infrared scanning beam generated by the first infrared scanning beam generator, and a second reference sensor for generating a second reference signal upon detecting the infrared scanning beam generated by the second infrared scanning beam generator; a coordinates-inputting pen including a photodetector for detecting the infrared scanning beam, a pen-press switch for detecting the pen-press against the board, an electronic circuit for outputting time sequential signals based on a detection signal from the photodetector and an ON/OFF signal from the pen-press switch, and a light-emitting element for generating an optical signal upon receiving the time sequential signals output from the electronic circuit; a light receiver arranged away from the coordinates-inputting pen for detecting the optical signal generated from the light-emitting element of the coordinates-inputting pen; and an electronic board controller for determining location coordinates of the coordinate inputting pen based on the outputs from the first and second reference sensors and the light receiver.
The coordinates-inputting pen may have a click switch, in which case, the electronic circuit outputs time sequential signals based on a detection signal from the photodetector, an ON/OFF signal from the pen-press switch and an ON/OFF signal from the click switch.
Preferably, the electronic circuit of the coordinates-inputting pen outputs encoded time sequential signals with obtained by adding recognition codes to the detection signal from the photodetector and the ON/OFF signal from the switch (e.g., a pen-press switch or a click switch). Addition of the recognition codes reduces transmission error of signals and enhances resistance against foreign noise.
Preferably, the electronic board controller calculates coordinates of the coordinates-inputting pen immediately upon receiving a code based on the detection signal from the photodetector of the coordinates-inputting pen, and affirm the calculated coordinates after confirming the recognition codes. By this configuration, time from the pen to capture the infrared scanning beam until the electronic board outputs the coordinate information of the pen can be shortened, thereby realizing rapid processing.
Wavelength xcex1 of the infrared light generated from first and second infrared scanning beam generators and wavelength xcex2 of the light generated from the light-emitting elements of the coordinates-inputting pen are made different, preferably. xcex1 less than xcex2. If xcex0 less than xcexa less than xcex1 less than xcexb less than xcex2, and xcex0 is within a visible range, an optical filter which transmits only light with a wavelength longer than wavelength xcexa is provided in front of the photodetector mounted on the coordinates-inputting pen while an optical filter which transmits only light with a wavelength longer than wavelength xcexb is provided in front of the light receiver for receiving an optical signal generated from the light-emitting element of the pen. As a result, signals do not interfere with each other as caused by positions or light intensities of the light sources.
The electronic board controller allows a light source in the infrared scanning beam generator to emit light when the electronic board controller judges that the pen-press signal is ON, and the electronic board controller suspends the light source in the infrared scanning beam generator from emitting light when the electronic board controller judges that the pen-press signal has been OFF for a predetermined time. Preferably, the infrared scanning light is emitted when the coordinates-inputting pen is touching the board for drawing (or writing) and is suspended when the pen leaves the board after the drawing (or writing).
Desirably, the electronic board controller suspends a light source in the first infrared scanning beam generator from emitting light while allowing a light source in the second infrared scanning beam generator to emit light when the electronic board controller judges that a photodetecting signal is generated from the coordinates-inputting pen during the generation of the infrared scanning beam by the first infrared scanning beam generator. The electronic board controller suspends the light source in the second infrared scanning beam generator from emitting light while allowing the light source in the first infrared scanning beam generator to emit light when the electronic board controller judges that a photodetecting signal is generated from the coordinates-inputting pen during the generation of the infrared scanning beam by the second infrared scanning beam generator. By such control, the response for detecting the coordinates of the coordinates-inputting pen can be enhanced, as compared to the case where the first and second infrared scanning beam generators alternately generate scanning beams at predetermined cycles.
The electronic board system of the invention may further comprise: a computer for receiving the coordinates information of the coordinates-inputting pen from the electronic board controller; and a display means connected to the computer for displaying a mark on the board based on the coordinates information.
A coordinates-inputting pen of the invention is used for inputting coordinates by detecting two infrared scanning beams alternately rotationally scanning in parallel to a surface of a board for specifying location coordinates of a pen. This coordinate inputting pen comprises: a shaft; a light receiver arranged on the tip of the shaft such that it can move in the shaft direction; a pen-press switch for generating ON/OFF signal according to the position of the light receiver in the shaft direction; an electronic circuit for outputting encoded time sequential signals obtained by adding recognition signals to the detection signal of the infrared scanning beam by the light receiver and the ON/OFF signal from the pen-press switch; and a light-emitting element for generating an optical signal in response to the time sequential signals output from the electronic circuit.
The light receiver may comprise a transparent conical member with a rough surface and a light-emitting element for detecting an infrared ray scattered inside the conical member.
The coordinates-inputting pen of the invention my further comprise a click switch. In this case, the electronic circuit outputs encoded time sequential signals obtained by adding recognition signals to the detection signal from the light receiver, an ON/OFF signal of the pen-press switch, and the ON/OFF signal of the click switch.